Viruses, Cell Structure, Cell Transport And Mitosis 3

Question 1

Replication of viruses

Answer 1

Attach to specific host cells using their attachment proteins which are complementary to receptors on the cell surface membrane of host cells
Inject nucleic acid
Nucleic acid is a set of instructions to direct the replication of more virus particles using organelles of host cell
This involves producing copies of viral nucleic acids and proteins to form complete viruses which are released by lysis

Question 2

Prokaryotes

Answer 2

Small single celled organisms with no nucleus and no membrane bound organelles
Always contains a cell wall, cell surface membrane, circular DNA, ribosomes and cytoplasm

Question 3

Eukaryotes

Answer 3

Characterised by the presence of a nucleus and cytoplasm containing many cell organelles

Question 4

Nucleus

Answer 4

Contains genetic material

Bound by a double membrane, the nuclear envelope which has nuclear pores allowing communication with cytoplasm

Question 5

Ribosomes

Answer 5

Made up of protein and RNA

used in protein synthesis, joining amino acids together

Question 6

Endoplasmic reticulum

Answer 6

Rough - has ribosomes that produce secretory proteins which are sent to Golgi apparatus for modification
Smooth - involved in production and transport of lipids

Question 7

Golgi apparatus and Golgi vesicles

Answer 7

Adds carbohydrates to proteins to form glycoproteins
Packages proteins into vesicles for secretion
Produces lysosomes that release lysozymes

Question 8

Lysosomes

Answer 8

Sacs containing hydrolytic enzymes surrounded by a single membrane
Digest material taken in by phagocytosis
Non functioning organelles are engulfed
Release of enzymes outside cell

Question 9

Mitochondria

Answer 9

Produce ATP
Bound by 2 membranes forming an envelope around an inner Matrix
Folds of the inner membrane are called the cristae (where respiration happens)

Question 10

Chloroplasts

Answer 10

Found in photosynthetic plant cells and algae
Surrounded by an envelope which encloses a membrane system consisting of thylakoids which form stacks GRANA
GRANA provide a large SA for chlorophyll molecules

Question 11

What do eukaryotic plant cells have that animal cells don’t?

Answer 11

Cell wall providing support strength and shape
Chloroplasts containing chlorophyll
Large vacuole containing soluble salts and sugars

Question 12

Cell differentiation

Answer 12

Cells form tissues (perform a specific function)
Organ consists of different tissues
System consists of 2 or more organs

Question 13

How are epithelial cells in the small intestine adapted for the absorption of digested food products?

Answer 13

Cell surface membrane is folded into micro villi providing large SA
Numerous mitochondria provide ATP for the active uptake of digested food

Question 14

Cell fractionation

Answer 14

Cells are broken by homogenising a tissue in cold isotonic buffer solution
Isotonic solution prevents osmotic moment of water
Low temp prevents the action of enzymes
Buffer solution maintains ph so proteins are not denatured

Question 15

Ultracentrifugation

Answer 15

Filtered to remove cell debris e.g. Cell walls
Homogenate is centrifuges at low speed - densest organelles form a pellet
Supernatant liquid is spun at higher speed for longer
Organelles are isolated - nucleus, mitochondria & chloroplasts, ER and soluble proteins

Question 16

Diffusion

Answer 16

Net movement of molecules from a high conc to a low conc

Passive

Question 17

Facilitated diffusion

Answer 17

Involves channel and carrier proteins

Passive

Question 18

Active transport

Answer 18

Movement of molecules through a partially permeable membrane by carrier proteins against a conc gradient
Requires ATP
Factors that decrease rate are lowered temp, lack of oxygen, metabolic and respiratory inhibitors

Question 19

Osmosis

Answer 19

Net movement of water molecules from a dilute solution to a concentrated solution across a partially permeable membrane

Question 20

Water potential

Answer 20

Tendency of water to move my osmosis and leave a solution
More solute means more negative WP
Water always move to a more negative WP

Question 21

Mitosis

Answer 21

Nuclear division that produces cells that are genetically identical

Question 22

interphase

Answer 22

DNA content is doubled
Increase in protein synthesis
Cell organelles are replicated

Question 23

1 prophase

Answer 23

Each chromosome shortens and thickens
Centrioles move to opposite poles of cell
Nuclear membrane breaks down

Question 24

2 metaphase

Answer 24

Each chromosome moves to equator of spindle and attaches to it via centromere

Question 25

3 anaphase

Answer 25

Centromere splits and sister chromatids separate

Sister chromatids pulled to opposite poles of cell

Question 26

4 telophase

Answer 26

Chromatids begin to uncoil
Nuclear membrane reforms
Two cells are genetically identical

Question 27

6 cytokinesis

Answer 27

Splitting of the cytoplasm in 2

Question 28

Cancer and the cell cycle

Answer 28

Caused by uncontrolled growth and rapid division of cells which damages genes that regulate mitosis resulting in a tumour

Question 29

Binary fission

Answer 29

1 cells divides into 2 cells involving the replication of circular DNA and plasmids, and division of cytoplasm to produce 2 daughter cells
Population in the nth generation = 2n